Title:
Potential role of local vs. global impedance measurement in ablation procedures

Authors:
Elena Pesch, Johannes Siebermair, Verena Marschall, Nadine Vonderlin, Miriam Köhler, Lisa Riesinger, Elif Kaya, Obayda Azizy, Florian Bruns, Tienush Rassaf, Reza Wakili

Aims
The „INTELLANAVTM MIFI OPEN-IRRIGATEDR“ ablation catheter provides new impedance technology (direct sense; DS) in order to determine tissue contact and to allow for sufficient and safe lesion creation. This novel catheter enables local impedance measurement between distal catheter electrodes below the tip in addition to the conventional generator impedance (GI). Our study aimed to evaluate the potential of local impedance (LI) measurement as periprocedural parameter with respect to tissue properties und lesion generation.

Methods and Results
We included 71 consecutive patients undergoing catheter ablation for any heart rhythm disorder with the DS-catheter from August 2017 to January 2019, guided by a 3D-mapping system. The generator and local impedance values were recorded simultaneously during ablation. Overall, 1827 radiofrequency (RF) applications were evaluated. The mean bloodpool impedance value was 97 ± 13.9 Ohm with LI. After establishing tissue contact, the baseline local impedance values were significantly different within the left atrium (LA), left ventricle (LV), right atrium (RA) and right ventricle (RV) (p<0.01;**)(figure A). We observed differences in the local baseline impedance values between the LA vs. LV (107.5 vs. 100.7**), in LA vs. RA (107.5 vs. 100.5**), and LV vs. RV (100.7 vs.107.9, p<0.05,*), and RA and RV ( 100.5 vs. 107.9*), respectively. Overall, the mean baseline LI was significantly lower compared to baseline generator impedance (106 ± 14 Ohm vs. 151 ± 19 Ohm **). In the LI-cohort the local impedance drop (15.6 ± 9.5 Ohm) was three-fold higher as GI drop (4,9 ± 7.4 Ohm), Figure B and C). The local baseline impedance was significantly associated with the local
impedance drop (R²=0.26**).

Conclusion
Local impedance seems to be distinct from global generator impedance measurement providing potential further information regarding chamber-specific impedance properties in the heart. Furthermore, local impedance kinetics seem to reflect a broader spectrum of ablation-dependent impendence drop, which was directly correlated to baseline LI values and therefore seem to be a promising surrogate parameter for lesion generation during ablation.